This invention relates to a method for the inhibition of neoplastic cells, for example, for the treatment or prevention of precancerous lesions or other neoplasias in mammals.
Each year in the United States alone, untold numbers of people develop precancerous lesions, which is a form of neoplasia, as discussed below. Such lesions exhibit a strong tendency to develop into malignant tumors, or cancer. Such lesions include lesions of the breast (that can develop into breast cancer), lesions of the skin (that can develop into malignant melanoma or basal cell carcinoma), colonic adenomatous polyps (that can develop into colon cancer), and other such neoplasms. Compounds that prevent or induce the remission of existing precancerous or cancerous lesions or carcinomas would greatly reduce illness and death from cancer.
For example, approximately 60,000 people die from colon cancer, and over 150,000 new cases of colon cancer are diagnosed each year. For the American population as a whole, individuals have a six percent lifetime risk of developing colon cancer, making it the second most prevalent form of cancer in the country. Colon cancer is also prevalent in Western Europe. It is believed that increased dietary fat consumption is increasing the risk of colon cancer in Japan.
In addition, the incidence of colon cancer reportedly increases with age, particularly after the age of 40. Since the mean ages of populations in America and Western Europe are increasing, the prevalence of colorectal cancer should increase in the future.
To date, little progress has been made in the prevention and treatment of colorectal cancer, as reflected by the lack of change in the five-year survival rate over the last few decades. The only cure for this cancer is surgery at an extremely early stage. Unfortunately, most of these cancers are discovered too late for surgical cure. In many cases, the patient does not experience symptoms until the cancer has progressed to a malignant stage.
In view of these grim statistics, efforts in recent years have concentrated on colon cancer prevention. Colon cancer usually arises from pre-existing benign neoplastic growths known as polyps. Prevention efforts have emphasized the identification and removal of colonic polyps. Polyps are identified by x-ray and/or colonoscopy, and usually removed by devices associated with the colonoscope. The increased use of colon x-rays and colonoscopies in recent years has detected clinically significant precancerous polyps in four to six times the number of individuals per year that acquire colon cancer. During the past five years alone, an estimated 3.5 to 5.5 million people in the United States have been diagnosed with adenomatous colonic polyps, and it is estimated that many more people have or are susceptible to developing this condition, but are as yet undiagnosed. In fact, there are estimates that 10-12 percent of people over the age of 40 will form clinically significant adenomatous polyps.
Removal of polyps has been accomplished either with surgery or fiber-optic endoscopic polypectomyxe2x80x94procedures that are uncomfortable, costly (the cost of a single polypectomy ranges between $1,000 and $1,500 for endoscopic treatment and more for surgery), and involve a small but significant risk of colon perforation. Overall, about $2.5 billion is spent annually in the United States in colon cancer treatment and prevention.
In the breast, breast cancer is often treated surgically, often by radical mastectomy with its painful aftermath. Such surgery is costly, too.
As indicated above, each lesion carries with it a chance that it will develop into a cancer. The likelihood of cancer is diminished if a precancerous lesion is removed. However, many of these patients demonstrate a propensity for developing additional lesions in the future. They must, therefore, be monitored periodically for the rest of their lives for reoccurrence.
In most cases (i.e. the cases of sporadic lesion formation, e.g. so-called common sporadic polyps), lesion removal will be effective to reduce the risk of cancer. In a small percentage of cases (i.e. cases where numerous lesions form, e.g. the so-called polyposis syndromes), removal of all or part of the effected area (e.g. the colon) is indicated. For example, the difference between common sporadic polyps and polyposis syndromes is dramatic. Common sporadic polyp cases are characterized by relatively few polyps which can usually be removed leaving the colon intact. By contrast, polyposis syndrome cases can be characterized by many (e.g. hundreds or more) of polypsxe2x80x94literally covering the colon in some casesxe2x80x94making safe removal of the polyps impossible short of surgical removal of the colon.
Because each lesion carries with it a palpable risk of cancerous development, patients who form many lesions (e.g. polyposis syndrome patients) invariably develop cancer if left untreated. Surgical removal of the colon is the conventional treatment in polyposis patients. Many polyposis patients have undergone a severe change in lifestyle as a result of the disfiguring surgery. Patients have strict dietary restrictions, and many must wear ostomy appliances to collect their intestinal wastes.
The search for drugs useful for treating and preventing cancer is intensive. Indeed, much of the focus of cancer research today is on the prevention of cancer because chemotherapy for cancer itself is often not effective and has severe side effects. Cancer chemoprevention is important for recovered cancer patients who retain a risk of cancer reoccurrence. Also, cancer prevention is important for people who have not yet had cancer, but have hereditary factors that place them at risk of developing cancer. With the development of new genetic screening technologies, it is easier to identify those patients with high-risk genetic factors, such as the potential for polyposis syndrome, who would greatly benefit from chemopreventative drugs. Therefore, finding such anti-cancer drugs that can be used for prolonged preventive use is of vital interest.
Known chemopreventative and chemotherapeutic drugs are believed to kill cancer cells by inducing apoptosis, sometimes referred to as xe2x80x9cprogrammed cell death.xe2x80x9d Apoptosis naturally occurs in virtually all tissues of the body, and especially in self-renewing tissues such as bone marrow, immune cells, gut, liver and skin. Apoptosis plays a critical role in tissue homeostasis, that is, it ensures that the number of new cells produced are correspondingly offset by an equal number of cells that die. For example, the cells in the intestinal lining divide so rapidly that the body must eliminate cells after only three days in order to prevent the overgrowth of the intestinal lining.
Recently, scientists have realized that abnormalities of apoptosis can lead to the formation of precancerous lesions and carcinomas. Also, recent research indicates that defects in apoptosis play a major role in other diseases in addition to cancer. Consequently, compounds that modulate apoptosis could be used to prevent or control cancer, as well as used in the treatment of other diseases.
Unfortunately, even though known chemotherapeutic drugs may exhibit such desirable apoptosis effects, most chemotherapeutic drugs have serious side effects that prohibit their long-term use, or use in otherwise healthy individuals with precancerous lesions. These side effects, which are a result of the high levels of cytotoxicity of the drugs, include hair loss, weight loss, vomiting, immune suppression and other toxicities. Therefore, there is a need to identify new drug candidates for therapy that do not have such serious side effects in humans.
In recent years, several non-steroidal anti-inflammatory drugs (xe2x80x9cNSAIDsxe2x80x9d), originally developed to treat arthritis, have shown effectiveness in inhibiting and eliminating colonic polyps. Polyps virtually disappear when the patients take the drug, particularly when the NSAID sulindac is administered. However, the prophylactic use of currently available NSAIDs, even in polyposis syndrome patients, is marked by severe side reactions that include gastrointestinal irritations, perforations, ulcerations and kidney toxicity. Once NSAID treatment is terminated due to such complications, the polyps return, particularly in polyposis syndrome patients.
Sulindac has been particularly well received among the NSAIDs for polyp treatment. Sulindac is a sulfoxide compound that itself is believed to be inactive as an anti-arthritic agent. The sulfoxide is reportedly converted by liver enzymes to the corresponding sulfide, which is acknowledged to be the active moiety as a prostaglandin synthesis inhibitor. The sulfide, however, is associated with the side effects of conventional NSAIDs. The sulfoxide is also known to be metabolized to a sulfone compound that has been found to be inactive as an inhibitor of prostaglandin synthesis but active as an inhibitor of precancerous lesions.
This invention includes a method of inhibiting neoplastic cells by exposing those cells to a pharmacologically effective amount of those compounds described below. Such compounds are effective in modulating apoptosis and eliminating and inhibiting the growth of neoplasias such as precancerous lesions, but are not characterized by the severe side reactions of conventional NSAIDs or other chemotherapeutics.
The compounds of that are useful in the methods of this invention include those of Formula I: 
wherein
X is selected from the group consisting of a direct bond, C1-4 alkylene, C1-4 alkyleneoxy, C1-4 alkoxyphenyl or phenyl C1-4 alkylene;
Y is selected from the group consisting of a direct bond or C1-2 alkyl;
R1 is selected from the group consisting of (i) 5-15 membered cyclic or branched chain heterocompound which includes one or two selected from a group consisting of nitrogen, oxygen and sulfur and which is substituted with one or two selected from a group consisting of hydrogen, halogen, nitro, hydroxy, C1-6 alkyl, C3-6 alkenyl and halogen C1-4 alkoxy, (ii) C4-10 carbocyclic compound or (iii) hydroxy C1-4 alkoxy;
R2 is selected from the group consisting of 5-15 membered cyclic or branched chain heterocompound which includes one or two selected from a group consisting of nitrogen, oxygen and sulfur and which is substituted with one or two selected from a group consisting of hydrogen, hydroxy, halogen, nitro, hydroxy C1-5 alkyl C1-6 alkyl, C3-6 alkenyl, and halogen C1-4 alkoxy;
R3 is selected from the group consisting of hydrogen, xe2x80x94C(O)R4, or xe2x80x94S(O)2R5;
R4 and R5 are each independently selected from the group consisting of hydroxy, C1-6 alkyl, C3-7 cycloalkyl, C3-6 alkenyl, halogen C1-6 alkyl, halogen, C2-6 alkenyl and C1-4 alkoxy; or R4 and R5 represent each independently 
and R6 is selected from a group consisting of hydrogen, hydroxy, C1-6 alkyl, C3-6 alkenyl, halogen, C1-6 alkyl, halogen, nitro and C1-4 alkoxy.
The compounds of formula I may have optical isomers or geometrical isomers. These isomers are included in practice of the methods of the present invention.
As indicated above, this invention relates to a method for inhibiting neoplasia, particularly cancerous and precancerous lesions by exposing the affected cells to a compound of Formula I above.
Preferably, such compounds are administered without therapeutic amounts of an NSAID.
The present invention is also a method of treating mammals with precancerous lesions by administering a pharmacologically effective amount of an enterically coated pharmaceutical composition that includes compounds of this invention.
Also, the present invention is a method of inhibiting the growth of neoplastic cells by exposing the cells to an effective amount of compounds of Formula I, wherein R1 through R3 are defined as above.
In still another form, the invention is a method of inducing apoptosis in human cells by exposing those cells to an effective amount of compounds of Formula I to those cells sensitive to such a compound.
As used herein, the term xe2x80x9cprecancerous lesionxe2x80x9d includes syndromes represented by abnormal neoplastic, including dysplastic, changes of tissue.
Examples include adenomatous growths in colonic, breast or lung tissues, or conditions such as dysplastic nevus syndrome, a precursor to malignant melanoma of the skin. Examples also include, in addition to dysplastic nevus syndromes, polyposis syndromes, colonic polyps, precancerous lesions of the cervix (i.e., cervical dysplasia), prostatic dysplasia, bronchial dysplasia, breast, bladder and/or skin and related conditions (e.g., actinic keratosis), whether the lesions are clinically identifiable or not.
As used herein, the term xe2x80x9ccarcinomasxe2x80x9d refers to lesions that are cancerous. Examples include malignant melanomas, breast cancer, and colon cancer.
As used herein, the term xe2x80x9cneoplasmxe2x80x9d refers to both precancerous and cancerous lesions.
It will also be appreciated that a compound of Formula I or a physiologically acceptable salt or solvate thereof can be administered as the raw compound, or as a pharmaceutical composition containing either entity.
Compounds useful in the methods of this invention are preferably formulated into compositions together with pharmaceutically acceptable carriers for oral administration in solid or liquid form, or for rectal administration, although carriers for oral administration are most preferred.
Pharmaceutically acceptable carriers for oral administration include capsules, tablets, pills, powders, troches and granules. In such solid dosage forms, the carrier can comprise at least one inert diluent such as sucrose, lactose or starch. Such carriers can also comprise, as is normal practice, additional substances other than diluents, e.g., lubricating agents such as magnesium stearate. In the case of capsules, tablets, troches and pills, the carriers may also comprise buffering agents. Carriers such as tablets, pills and granules can be prepared with enteric coatings on the surfaces of the tablets, pills or granules. Alternatively, the enterically coated compound can be pressed into a tablet, pill, or granule, and the tablet, pill or granules for administration to the patient. Preferred enteric coatings include those that dissolve or disintegrate at colonic pH such as shellac or Eudraget S.
Pharmaceutically acceptable carriers include liquid dosage forms for oral administration, e.g. pharmaceutically acceptable emulsions, solutions, suspensions, syrups and elixirs containing inert diluents commonly used in the art, such as water. Besides such inert diluents, compositions can also include adjuvants such as wetting agents, emulsifying and suspending agents, and sweetening, flavoring and perfuming agents.
Pharmaceutically acceptable carriers for rectal administration are preferably suppositories that may contain, in addition to the compounds of Formula I, excipients such as cocoa butter or a suppository wax.
The pharmaceutically acceptable carrier and compounds of this invention are formulated into unit dosage forms for administration to a patient. The dosage levels of active ingredient (i.e. compounds of this invention) in the unit dosage may be varied so as to obtain an amount of active ingredient effective to achieve lesion-eliminating activity in accordance with the desired method of administration (i.e., oral or rectal). The selected dosage level therefore depends upon the nature of the active compound administered, the route of administration, the desired duration of treatment, and other factors. If desired, the unit dosage may be such that the daily requirement for active compound is in one dose, or divided among multiple doses for administration, e.g., two to four times per day.
The pharmaceutical compositions of this invention are preferably packaged in a container (e.g. a box or bottle, or both) with suitable printed material (e.g. a package insert) containing indications, directions for use, etc.
For administration to humans in the curative or prophylactic treatment of the disorders identified above, oral dosages of a compound of Formula I will generally be in the range of from 0.5-800 mg daily for an average adult patient (70 kg). Thus for a typical adult patient, individual tablets or capsules contain from 0.2-400 mg of active compound, in a suitable pharmaceutically acceptable vehicle or carrier, for administration in single or multiple doses, once or several times per day. Dosages for intravenous, buccal or sublingual administration will typically be within the range of from 0.1-400 mg per single dose as required. In practice, the physician will determine the actual dosing regimen that will be most suitable for an individual patient and it will vary with the age, weight and response of the particular patient.
A process for producing compounds of formula I comprises (a) reacting a compound of formula III: 
with a compound of formula III-a:
HNxe2x80x94Xxe2x80x94R1
which X and R1 represent the same as defined above, to give a compound of formula IV: 
which X and R1 represent the same as defined above,
(b) reacting the compound IV with a compound of the general formula IV-a: Yxe2x80x94R2 in which Y and R2 represent the same as defined above, to give a compound of the general formula V: 
in which X, R1 and R2 represent the same as defined above, (c) reducing the compound V to give a compound of the general formula VI: 
in which X, Y, R1 and R2 represent the same as defined above, (d-i) reacting the compound VI with a compound of (VI-I): 
in which R4 is selected from a group consisting of hydroxy, C1-6 alkyl, C3-7 cycloalkyl, C3-6 alkenyl, halogen C1-6 alkyl, halogen C2-6 alkenyl and C1-4 alkoxy or R4 represents 
in which R6 is selected from the group consisting of hydrogen, hydroxy, C1-6 alkyl, C3-6 alkenyl, halogen C1-6 alkyl, halogen, nitro, and C1-4 alkoxy to give a compound of formula I-B: 
in which x, Y, R1, R2 and R5 are the same as defined above.
The compound III is reportedly described in WO 9510506 and, reportedly, can be prepared by reacting the compound 11 with phosphorus oxychloride in the presence of a base. N,N-diethyl-aniline, N,N-dimethylaniline or NN-diisopropylethylamine can be used as the base. As such, the reaction is carried out at a reflux temperature.
The compound IV can be prepared by reacting the compound III with the compound of formula III-a: HNxe2x80x94Xxe2x80x94R1 in which R1 is the same as defined above, preferably, using pyridine or triethylamine in solvent such as dichloromethane or acetonitrile at 0xc2x0 C. to room temperature (J. Med. Chem. 1994, 37, 2106).
The compound V can be prepared by dissolving the compound IV in a polar solvent and reacting the solution with the compound of the formula IV-a: Yxe2x80x94R2 in which R2 is the same as defined above, at 0xc2x0 C. to reflux temperature. Usually, the compound V is obtained as crystals in acetonitrile, ethanol or isopropanol.
The compound VI is obtained by reacting the compound V with iron and acid in polar solvent under reflux (see, e.g., WO 9518097) or by reacting the compound V with sodium borohydride and 5% palladium on activated carbon in solvent such as methanol or ethanol at 0xc2x0 C. to 25xc2x0 C. (Synthesis, 1994, 1437).
The compound 1-A is produced by reacting the compound VI with the compound VI-a: xe2x80x94C(O)R4 in which R4 is the same as defined above, using pyridine, triethylamine or N,N-diisopropyl ethyl amine as a base in solvent such as acetonitrile, dichloromethane or tetrahydrofurane at 0xc2x0 C. to reflux temperature.
The compound 1-B is produced by reacting compound VI with the compound VI-b: xe2x80x94S(O)2R5 in which R5 is as defined above, using pyridine or N,N-diisopropylethylamine as a base in solvent such as acetonitrile, dichloromethane or tetrahydrofurane at 0xc2x0 C. to 25xc2x0 C.